Chemical combination - Jamb Chemistry Past Questions and Answers

Question 86:

• JAMB 1998

90.0g of MgCI₂ was placed in 50.0cm³ of water to give a saturated solubility of the salt is 8.0 mol dm³ at the same temperature, what is the mass of the salt left undissolved at the given temperature?
(Mg = 24, Cl = 35.5)

A. 52.0g
B. 58.5g
C. 85.5g
D. 88.5g

Question 87:

• JAMB 1999

56.00cm³ of a gas at S.T.P. weighed 0.11g. What is the vapour density of the gas?
[Molar volume of a gas at S.T.P = 22.4dm³]

A. 11.00
B. 22.00
C. 33.00
D. 44.00

Question 88:

• JAMB 1999

Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
From the equation above, the mass of magnesium required to react with 250cm3 of 0.5M HCl is
[Mg = 24]

A. 0.3g
B. 1.5g
C. 2.4g
D. 3.0g

Question 89:

• JAMB 1999

A gaseous metallic chloride MCl_x consists of 20.22% of M by mass. The formula of the chloride is
[M = 27, Cl = 35.5]

A. MCl
B. MCl₂
C. MCl₃
D. M₂Cl₆

Question 90:

• JAMB 1999

From the diagram above the mass of crystals deposited when 1 dm ³ of a saturated solution of NaCl is cooled from 80 ^oC to 60^oC is
[Na = 23, Cl = 35.5]

A. 117.00 g
B. 58.50 g
C. 11.70 g
D. 5.85 g